1. Field of the Invention
This invention relates to liquid-liquid ion exchange of alkali metal ions. More specifically, the invention provides a process whereby potassium is recovered from an aqueous phase by ion exchange with a polyol-boron-alkali metal complex.
2. Description of the Prior Art
In the past, borax and other boron containing materials as well as salts of the alkali metals have been recovered from alkaline brine solutions by evaporation or by cooling the brine so that the salt will crystallize from the solution.
More recently, solvent extraction processes such as those disclosed in U.S. Pat. Nos. 2,969,275 and 3,111,383 have been developed to recover boron values. When such solvent extraction processes are employed to recover boron values from brine, an alkali metal ion, such as sodium or potassium also is co-extracted along with the boron values. Such co-extraction from alkaline brines is desirable as long as a market exists for salts of the recovered mixed metallic ions. Since potassium is of greater commercial value than sodium, it would be desirable in such boron extraction processes to exchange at least a portion of the sodium values contained therein for potassium values.
Other processes for the recovery of boron or alkali metal salts from alkaline brines are disclosed in, for example: U.S. Pat. Nos. 2,726,138; 2,969,275; 3,179,503; 3,424,563; 3,433,604; 3,493,3493,582,290; 3,598,547; 3,598,548; 3,741,731; and 3,812,238.